Grinding machine



Nov. 12, 1935. L E, R055 2,021,024

GRINDING MACHINE Filed Oct. 22, 1954 2 Sheets-Sheet` l rToP/YEY Nov. l2, 1935. .1 ll.. E. Ross A GRINDING MACHINE Filed oct. 22, 1934 2 Sheets-Sheet 2 ql. r

m A @w Sw w NN ZN VEN ro 7 eanar'a/ z5. F055. y@ i4 froP/vgy Patented Nov. l2, 1935 UNITED STATES FATENT OFFICE 5 Claims.

This invention relates generally to 'grinding` machines, and more particularly, to a certain new and useful improvement in surface grinders of the abrasive belt type.

My invention has for its prime object the provision of a grinding machine especially, though not exclusively, adapted for finishing or grinding iillets and concave and irregular surfaces in general.

My invention has for another object the provision of a grinding machine of the type stated, in which the working surface of the belt is cushioned or resiliently supported, so that the belt may readily flex or yield to suit the contour of the work while elastically resisting such flexure suiiiciently for eiciently performing its Yintended grinding functions.

VMy invention has for still another object lthe provision of a grinding machine of the type mentioned `in which one of its belt-supporting pulleys is readily adjustable, so as to train the belt to the desired usable position thereof on the pulley, that is to say, either `toward the center or toward a side margin of the pulley, such result being obtainable without the interposition of belt guides or other members engaging the side margins of the belt.

My invention has for a further object the provision, in a grinding machine of the abrasive-belt type, of a pulleysupport for the grinding belt provided With an elastic rim yieldable to grinding` pressure over its entire face and especiallyflexible at its side circumferential margins for yielding to the working of concave objects at the side margins of the belt.

My invention has for a still further object the provision of a portable or bench type of abrasivebelt grinding machine which is simple and compact in structure and inexpensive to manufacture and maintain in usable condition, and to improve the construction of abrasive-belt grinders in general.

And with the above and other objects in View, my invention resides in the novel form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings `(two sheets) Figure 1 is a top plan View of an abrasive-belt type of grinding machine embodying my invention;

Figure 2 is a similar View showing the motor shifted longitudinally on the base for tensioning the abrasive-belt;

Figure 3 is a side elevational view of the machine;

pos-es shortly appearing. Q15

Figure 4 is a fragmentary sectional view taken approximately along the line 4-45, Figure 2;

Figure 5 is a fragmentary sectional view taken approximately along the line 5 5, Figure 3, a shifted position of the belt being shown by dot- 5.'5 dash lines; and l Figure 6 is a view similar to Figure 5, showing the belt in use, the work being shown in dot-dash lines.

Referring now more in detail and by reference tu, characters to the drawings, which illustrate a preferred embodiment of the invention, the machine includes a suitably elongated substantially rectangular hollow base I, which at its rear end and on its upper surface supports a pair of transversely spaced longitudinal rails or slide-ways 2.

Slidably mounted on the rails 2 for reciprocation, is a carriage 3, which supports, in turn, a suitable prime-mover, such as an electric-motor 4, provided on its main-shaft with a suitably diigt, mensioned pulley 5 for purposes presently appearing. v

Depending from the carriage 3 in and through a suitable longitudinal slot provided for the purpose in the upper wall of the base I, is a lug 6 having .25 a'pivot-connection at its lower end with one end of a link l, which, in turn, extends forwardly within the confines of the base I, and at its other end is pivotally connected with a hand-lever 8 at a point intermediate the ends thereof. The lever El also, in turn, is pivoted at one end, as at 9, to the base I and at its free end projects outwardly through a slot It provided in a side wall of the base I,-the latter being arcuately contoured or rounded away suitably for the purpose, as best seen in Figures 1 and'2.

Attached to and upon the inner face of the side wall ofthe base adjacent the slot I0, is a ratchet-bar or serrated member II, whose teeth I2 are adapted for engagement by a detent I3 de- 40 position of the carriage 3 on the rails 2, for pur- At its forward end, and at the corner thereof substantially opposite to the location of the lever 8, the base i is provided with a lateral projection or bracket It carrying an upstanding pivot pin i5, on which is pivotally or swivelly mounted l5() a pulley-stand I5, extending inwardly from which is an arm Il having a slot-and-pin engagement, as at I8, with a nut i9 working on an elongated tween a pair of longitudinally spaced bearings 2I 55 suitably upstanding from the upper surface of the the cushion rim-facing 28 is beveled or undercut, Las'at 29 in Figure 5, for thus progressively dibase l.

VAt its forward end, thescrew 20 projects suitably beyond the forward bearing 2l and is equipped with a hand-wheelV 22 for manualV manipulation, with ensuing traverse of the nut I3 Y on the screw 20, whereby, as desired, the stand I6 may be rotatably shifted on its pivot I5, with consequences presently to be described.

Extending obliquely upwardly and forwardly -fromr Vthebase of the stand I6, isa standard 23, which at its upper free end supports an inwardly extending lateral stub-shaft 24 carrying a suit-V able bearing 25, preferably of the annular ball- Vbearing type, for rotatably supporting a belt-supporting pulley 26, as best seen in -Figures .1,- 2, and 3. Y. 'A

The pulley 26, which is of rigid constructin'and preferably is made of aluminum orv other -light weight metallic material, is provided with a rela- `"tively wide` rim-21, which is circumferentially embrac'ei'dby anannular cushionfacing or lagging Y 28 composed of a suitable resilient or elastic material, preferably rubber or the like.

. On the underside of its lateral or side margins,

minishing' the resistance, or weakening the strength, of the cushion toward its side margins, whereby vthe cushion 2871s atsuch point more especially flexible or yieldably responsive to radial pressure applied on the pulley during the working of 'the machine, Vas will presently be more particularly pointedY out.

On and between the driving ,and driven pulleys 5 and 26, respectively, is trained an abrasive-belt Curreht for motivatingthe motor 4 may be suptension cord or cable 3| attached to and leading suitably into the base I andprovided at its free end with a plug 32 for engaging a wall-socketor the like, not shown. In the conventional manner, aV manually operable snap switch 33 is mounted on the base I and connected in the circuit of the motor 4 for Vcontrolling the 4actuation thereof at the will of the operator' f i In use and operation, theY resilient rim-facing or` cushion 28 isemployed as the VAsupport; for the surface of the grinding belt 30 Where the grinding operation is to be'done. VWhen an article is to be ground, it is simply pressedV againstV lthe rapidly moving surface of the abrasive-belt as'it passes over the pulley 26. Y When, as in the use for which my grinder is particularly adapted, the surface to beground is Y of irregular shape, it will be vreadily understood' that the elastic cushion 28'whi`ch supports the belt r30 will yield tothe co-ntour of the work, thus enabling the polishing or grinding of such sur- 1 faces in a simple and facile manner.

Mlore' particularly,V when the surface to be` ground' includes a concave surface, such as a ginal side of the belt 3D. As has beensaid, the cushion 28 has a progressivelyincreasing degree of 'flexibility toward its side marginsdue to the undercutting 29; and hence, VwhenV Vthe work is applied tothe belt for-engaging the fillet with -the' marginal side thereof, the cushion 28 yields shape of the fillet, as clearly lshown in Figure 6, the work being therein indicated by the dot-dashV lines. It will be readily apparent that, in such `fillet Ygrinding work, the side margins of the belt 30 5 become moreor less rapidly -worn and ultimately useless for their intended purpose. In such event,

Ythe screw 20 is manipulated for rotating the stand l 6 on its pivot, i5, which, inY turn, shifts the pulley 26 laterally in an arcuate path to one side or the 10Y other of its normal position. The pulley v26 then al'sorhas a slight angular displacement with respect to the driving pulley 5whereby the belt 30V is caused to shift laterally on the pulley 26 until Y the worn marginrof'the belt projects over'and 15 -to one side of the cushion-rim 28, asV shown by dot-dash'lines in Figure 5. Y f

It is then a simple matter to cutoff Vthe worn margin of the belt 30 and totrain the belt over the pulley until the newly trimmed side margin 20 Y) of the belt is flush with tliecorresponding margin of the cushion 28, as shown by the full lines in Figure 5, the-belt 30 being thus, in a highly` expedient and facile manner, v,restored toits `original eifectiveness for filletgrinding purposes.

The hand-lever 8,-in co-operationY with the rack Y I I is employed for shifting themotor land'pulley 5 longitudinally in the plane of the belt and rearwardly` on the baseY l for tensioning the belt 30' between the pulleys 5 and-26, the co-operationof `-30 on the belt 30 Vfor causing the sameto hug the cushion 28 .with sufficient force Vto flex or bend the side margins of thebelt 3U ,over the undercut margins of the cushion 28, soV that the side Y margins of the belt V30'partake 'of a curvilinear ,4,9V

shape highly suitable Vfor fillet grinding purposesgas best seenV in Figure 2. Y v In such manner, the pressure applied on the.

w0rk,' for conforming the belt to the llet'con- Y tour, maybe considerably reduced, with Yconse- Vquent reduction inthe `wear andprolongation y of the life of thev belt. y The machine may be readily manufactured,

Y is sturdy and durable, and eficient in theY performance of its intended functions. 1 i

And it is to be understood that changesand modifications in Vthe form, construction, ar-

-rangement andcombination of the several'parts of the machine may be made and substituted for those herein shown and described without departingY from the Vnature and principle of -my Y invention.

Having thus-described my'invention, what I claim Aand desire to secure by Letters Patent is,-

l. A grinding machine including an abrasive@ -belt, anda Vpulley for supporting the working]V portion of the belt, said pulley comprising a rigid v vcenter provided with anV elastic coveringf on its rim, andthe covering at'its lateral margins being undercut providing a groove between the@i outer surface of the covering and the rim of Vth center.

i flllet or the like, the work is engaged with a mar- 2. InV a grinding machine, an abrasive belt,VV

Y and means including spaced pulleysV for sup-V turally weakened inY aside face for increasing its flexibility at its margin, whereby the lagging is marginally yieldingly conformable to the conf 3. In a grinding-machine, an abrasive belt,

and means including spaced pulleys for supporting the belt for movement, one of said pulleys comprising a rim and a rubber lagging embracing the rim, said lagging being undercut in its opposite side faces for increasing its exibility at its opposite margins, whereby the lagging is marginally elastically conformable to the contour of Work presented for grinding upon the belt at said pulley.

4. In a grinding-machine, an abrasive belt, spaced pulleys for supporting the belt for movement, means for tensioning the belt on the pulleys, and a resilient lagging on one of said pulleys marginally weakened for taking, on tensioning of the belt, a curvilinear shape relatively to said pulley.

5. In a grinding machine, an abrasive belt, spaced pulleys for supporting the belt for movement, means for tensioning the belt on the pulleys, and an elastic lagging on one of said pulleys having a recess in a side face for taking, on tensioning of the belt, a curvilinear shape relatively 

